What's the difference between the natural minor, the harmonic minor, and the melodic minor?

The natural minor scale has all the notes aCCORDING TO THE KEY SIGNATURE WITH NO ACCIDENTALS. tHE HARMONIC MONOR SHARPS THE SEVENTH DEGREE ON THE WAY UP AND DOWN. THE MELODIC MINOR SCALE SHARPS THE SIXTH AND THE SEVENTH, AND IS BACK TO NATURAL (KEY SIGNATURE) ON THE WAY DOWN.

EXAMPLE:

A MINOR NATURAL: ABCDEFGA, AGFEDCBA
A MINOR HARMONIC: ABCDEFG#A, AG#FEDCBA
A MINOR MELODIC: ABCDEF#G#A, AGFEDCBA

the natural minor is the regular minor scale, (step step half, step step step half...)
the harmonic minor is when the 6th and 7th step are raised a half note on the up down but normal on the way down.
the melodic minor is when the 7th step is raised a half step both ways.